On macOS, run a simple application with a modal dialog, like the one attached to this issue.

Follow these steps:
1. Run the application ("1. application.png")
2. Open the dialog ("2. application and dialog.png")
3. Press Ctrl+Up, to open Mission Control ("3. Mission control.png")
4. Select, and drag the main stage and move it to the top Spaces bar, after the existing desktops, to its own "java" space ("java space.png"), which simply will make the main stage to go fullscreen in its own space, while the dialog remains in the initial workspace/desktop.
5. From the top Spaces bar, go to the java desktop (or without Mission Control, press Control+Right until you reach it). You will hear a beep (due to the modal dialog), and immediately the space will change back to the initial desktop with the dialog ("orphan dialog.png").
6. Press OK to close the dialog, the app will crash.

This is the exception:

*** Terminating app due to uncaught exception 'NSGenericException', reason: 'NSWindowStyleMaskFullScreen cleared on a window outside of a full screen transition. Called from (
        0 AppKit 0x00000001877e25e0 __25-[NSWindow setStyleMask:]_block_invoke + 156
        1 AppKit 0x0000000186b729b0 NSPerformVisuallyAtomicChange + 108
        2 AppKit 0x00000001877e2490 -[NSWindow setStyleMask:] + 176
        3 libglass.dylib 0x00000001081106f8 Java_com_sun_glass_ui_mac_MacWindow__1setEnabled + 444
        4 ??? 0x0000000118f54500 0x0 + 4713694464
        5 ??? 0x0000000118f50950 0x0 + 4713679184
        6 ??? 0x0000000118f50950 0x0 + 4713679184
        7 ??? 0x0000000118f50950 0x0 + 4713679184
        8 ??? 0x0000000118f50950 0x0 + 4713679184
        9 ??? 0x0000000118f50ef0 0x0 + 4713680624
        10 ??? 0x0000000118f50950 0x0 + 4713679184
        11 ??? 0x0000000118f50950 0x0 + 4713679184
        12 ??? 0x0000000118f50950 0x0 + 4713679184
        13 ??? 0x0000000118f50950 0x0 + 4713679184
        14 ??? 0x0000000118f50950 0x0 + 4713679184
        15 ??? 0x0000000118f50950 0x0 + 4713679184
        16 ??? 0x0000000118f50950 0x0 + 4713679184
        17 ??? 0x0000000118f50950 0x0 + 4713679184
        18 ??? 0x0000000118f50950 0x0 + 4713679184
        19 ??? 0x0000000118f50950 0x0 + 4713679184
        20 ??? 0x0000000118f50950 0x0 + 4713679184
        21 ??? 0x0000000118f50950 0x0 + 4713679184
        22 ??? 0x0000000118f50950 0x0 + 4713679184
        23 ??? 0x0000000118f50ef0 0x0 + 4713680624
        24 ??? 0x0000000118f50950 0x0 + 4713679184
        25 ??? 0x0000000111d3f70c 0x0 + 4594071308
        26 ??? 0x0000000118f506e0 0x0 + 4713678560
        27 ??? 0x0000000111df3b34 0x0 + 4594809652
        28 ??? 0x0000000118f506e0 0x0 + 4713678560
        29 ??? 0x0000000118f506e0 0x0 + 4713678560
        30 ??? 0x0000000118f50950 0x0 + 4713679184
        31 ??? 0x0000000118f50950 0x0 + 4713679184
        32 ??? 0x0000000118f50950 0x0 + 4713679184
        33 ??? 0x0000000118f50950 0x0 + 4713679184
        34 ??? 0x0000000118f50ef0 0x0 + 4713680624
        35 ??? 0x0000000118f50950 0x0 + 4713679184
        36 ??? 0x0000000118f50ef0 0x0 + 4713680624
        37 ??? 0x0000000118f50950 0x0 + 4713679184
        38 ??? 0x0000000111d3f70c 0x0 + 4594071308
        39 ??? 0x0000000118f506e0 0x0 + 4713678560
        40 ??? 0x0000000111df3b34 0x0 + 4594809652
        41 ??? 0x0000000118f506e0 0x0 + 4713678560
        42 ??? 0x0000000118f506e0 0x0 + 4713678560
        43 ??? 0x0000000118f50950 0x0 + 4713679184
        44 ??? 0x0000000118f50950 0x0 + 4713679184
        45 ??? 0x0000000118f50950 0x0 + 4713679184
        46 ??? 0x0000000118f50ef0 0x0 + 4713680624
        47 ??? 0x0000000118f506e0 0x0 + 4713678560
        48 ??? 0x0000000118f50c80 0x0 + 4713680000
        49 ??? 0x0000000118f506e0 0x0 + 4713678560
        50 ??? 0x0000000118f50950 0x0 + 4713679184
        51 ??? 0x0000000118f50950 0x0 + 4713679184
        52 ??? 0x0000000118f50950 0x0 + 4713679184
        53 ??? 0x0000000118f4c114 0x0 + 4713660692
        54 libjvm.dylib 0x0000000108687d50 _ZN9JavaCalls11call_helperEP9JavaValueRK12methodHandleP17JavaCallArgumentsP10JavaThread + 992
        55 libjvm.dylib 0x00000001086fa798 _ZL20jni_invoke_nonstaticP7JNIEnv_P9JavaValueP8_jobject11JNICallTypeP10_jmethodIDP18JNI_ArgumentPusherP10JavaThread + 1036
        56 libjvm.dylib 0x00000001086ff248 jni_CallVoidMethod + 284
        57 libglass.dylib 0x000000010810a044 Java_com_sun_glass_ui_mac_MacView__1finishInputMethodComposition + 14664
        58 AppKit 0x0000000186c131e4 forwardMethod + 252
        59 AppKit 0x0000000187893c30 _routeMouseUpEvent + 132
        60 AppKit 0x00000001878939ac -[NSWindow(NSEventRouting) _reallySendEvent:isDelayedEvent:] + 440
        61 AppKit 0x0000000187893470 -[NSWindow(NSEventRouting) sendEvent:] + 372
        62 libglass.dylib 0x000000010810ea78 Java_com_sun_glass_ui_mac_MacView__1finishInputMethodComposition + 33660
        63 AppKit 0x00000001875a24ac -[NSApplication(NSEventRouting) sendEvent:] + 1276
        64 AppKit 0x000000018709c6ec -[NSApplication _handleEvent:] + 60
        65 AppKit 0x0000000186b49748 -[NSApplication run] + 408
        66 libglass.dylib 0x00000001080efb04 JNI_OnLoad + 9076
        67 Foundation 0x0000000183f820c4 __NSThreadPerformPerform + 264
        68 CoreFoundation 0x0000000182763ad8 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 28
        69 CoreFoundation 0x0000000182763a6c __CFRunLoopDoSource0 + 172
        70 CoreFoundation 0x00000001827637d8 __CFRunLoopDoSources0 + 232
        71 CoreFoundation 0x0000000182762468 __CFRunLoopRun + 820
        72 CoreFoundation 0x0000000182820898 _CFRunLoopRunSpecificWithOptions + 532
        73 libjli.dylib 0x00000001025e4f64 CreateExecutionEnvironment + 412
        74 libjli.dylib 0x00000001025e0a0c JLI_Launch + 560
        75 java 0x000000010259bbb4 main + 404
        76 dyld 0x0000000182305d54 start + 7184
)'
*** First throw call stack:
(
        0 CoreFoundation 0x00000001827b4770 __exceptionPreprocess + 176
        1 libobjc.A.dylib 0x0000000182292418 objc_exception_throw + 88
        2 CoreFoundation 0x00000001828837fc -[NSException initWithCoder:] + 0
        3 AppKit 0x00000001877e2618 __25-[NSWindow setStyleMask:]_block_invoke + 212
        4 AppKit 0x0000000186b729b0 NSPerformVisuallyAtomicChange + 108
        5 AppKit 0x00000001877e2490 -[NSWindow setStyleMask:] + 176
        6 libglass.dylib 0x00000001081106f8 Java_com_sun_glass_ui_mac_MacWindow__1setEnabled + 444
        7 ??? 0x0000000118f54500 0x0 + 4713694464
        8 ??? 0x0000000118f50950 0x0 + 4713679184
        9 ??? 0x0000000118f50950 0x0 + 4713679184
        10 ??? 0x0000000118f50950 0x0 + 4713679184
        11 ??? 0x0000000118f50950 0x0 + 4713679184
        12 ??? 0x0000000118f50ef0 0x0 + 4713680624
        13 ??? 0x0000000118f50950 0x0 + 4713679184
        14 ??? 0x0000000118f50950 0x0 + 4713679184
        15 ??? 0x0000000118f50950 0x0 + 4713679184
        16 ?
libc++abi: terminating due to uncaught exception of type NSException

The issue can be reproduced with any JavaFX version, including head.