report bad typer state error

Author: Alex1005a

compiler/src/dotty/tools/dotc/core/TyperState.scala

@@ -274,7 +274,7 @@ class TyperState() {
 
     if oldState != null && oldState.isCommittable then
       throw BadTyperStateAssertion(
-        i"$this attempted to take ownership of $tvar which is already owned by committable $oldState. Location: ${ctx.owner.showLocated}")
+        i"$this attempted to take ownership of $tvar which is already owned by committable $oldState")
     tvar.owningState = new WeakReference(this)
     ownedVars += tvar
 

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -4495,7 +4495,8 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
               && !ctx.mode.is(Mode.TypevarsMissContext)
               && !containsUninst(false, formal)
               && !isFullyDefined(formal, ForceDegree.none) then
-              constrainResult(tree.symbol, wtp, pt1)
+              try NoViewsAllowed.constrainResult(tree.symbol, wtp, pt1)
+              catch case ex: TyperState.BadTyperStateAssertion => report.error(s"Bad typer state: ${ex.getMessage}", tree.srcPos.endPos)
             val arg = inferImplicitArg(formal, tree.span.endPos)
 
             lazy val defaultArg = findDefaultArgument(argIndex)