Turn an assert into report_fatal_error since it's reachable based on user input

Bug found with AFL fuzz.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236076 91177308-0d34-0410-b5e6-96231b3b80d8

test/Bitcode/invalid.test

@@ -105,3 +105,8 @@ RUN: not llvm-dis -disable-output %p/Inputs/invalid-vector-element-type.bc 2>&1
 RUN:   FileCheck --check-prefix=ELEMENT-TYPE %s
 
 ELEMENT-TYPE: Invalid type
+
+RUN: not llvm-dis -disable-output %p/Inputs/invalid-array-op-not-2nd-to-last.bc 2>&1 | \
+RUN:   FileCheck --check-prefix=ARRAY-NOT-2LAST %s
+
+ARRAY-NOT-2LAST: Array op not second to last