If an erroneous regex pattern contains "\t" (horizontal tab HT), the ^ (diagnostic caret) symbol might be misplaced. For example:
```
jshell> Pattern.compile("\t**")
| Exception java.util.regex.PatternSyntaxException: Dangling meta character '*' near index 2
**
  ^
| at Pattern.error (Pattern.java:2028)
| at Pattern.sequence (Pattern.java:2203)
| at Pattern.expr (Pattern.java:2069)
| at Pattern.compile (Pattern.java:1783)
| at Pattern.<init> (Pattern.java:1430)
| at Pattern.compile (Pattern.java:1069)
| at (#2:1)
```
Compare that with this:
```
jshell> Pattern.compile(" **")
| Exception java.util.regex.PatternSyntaxException: Dangling meta character '*' near index 2
 **
  ^
| at Pattern.error (Pattern.java:2028)
| at Pattern.sequence (Pattern.java:2203)
| at Pattern.expr (Pattern.java:2069)
| at Pattern.compile (Pattern.java:1783)
| at Pattern.<init> (Pattern.java:1430)
| at Pattern.compile (Pattern.java:1069)
| at (#3:1)
```
This happens because when calculating required indentation, java.util.regex.PatternSyntaxException#getMessage translates "\t" into "\s" unlike, for example, com.sun.tools.javac.util.AbstractDiagnosticFormatter#formatSourceLine, which translates "\t" into "\t".