#2929 Handle null range in a safe way

Not quite sure how can this be, but technically range can be null.

Fixes #2929

plugin/core/src/main/java/com/perl5/lang/perl/idea/inspections/PerlUnreachableCodeInspection.java

@@ -86,7 +86,7 @@ private void registerReachableRange(@NotNull Instruction instruction) {
           return;
         }
         var elementRange = element.getTextRange();
-        if (elementRange.isEmpty()) {
+        if (elementRange == null || elementRange.isEmpty()) {
           return;
         }
         var rangesIterator = reachableRanges.iterator();