Synopsis Pattern matching has not been properly initialized.
Description Rascal:PatternMatching requires two ingredients:
  • One of the many Rascal:Patterns.
  • A non-void subject value to which the pattern is applied.
This error is generated when the subject is void.

Remedy: replace the subject by a non-void value.
Examples here is a (contrived) example that produces this error:
rascal>void dummy() { return; }
void (): void dummy();
rascal>int n := dummy();
|stdin:///|(9,5,<1,9>,<1,14>): Uninitialized pattern match: trying to match a value of the type 'void'
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