Bug fix. Have to arrange to only close a catch once. After the spacebug_3154ea2759

has been returned to placeholder values, closing with them as data leads
to memory corruption.

There's probably a better fix available because the error here feels like
it's rooted somewhere else, having us continue to check values we ought to
know have already been closed.

1 files changed, 3 insertions, 0 deletions

diff --git a/generic/tclAssembly.c b/generic/tclAssembly.c
index 6d5676b..d02721d 100644
--- a/generic/tclAssembly.c
+++ b/generic/tclAssembly.c
@@ -3984,6 +3984,9 @@ UnstackExpiredCatches(
 
     while (catchDepth > bbPtr->catchDepth) {
 	--catchDepth;
+	if (catches[catchDepth] == NULL) {
+	    continue;
+	}
 	range = envPtr->exceptArrayPtr + catchIndices[catchDepth];
 	range->numCodeBytes = bbPtr->startOffset - range->codeOffset;
 	catches[catchDepth] = NULL;