[BitcodeReader] Change assert to report_fatal_error

It can be triggered by user input.

Bug found with AFL fuzz.

llvm-svn: 238272

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -785,7 +785,8 @@ Constant *BitcodeReaderValueList::getConstantFwdRef(unsigned Idx,
     resize(Idx + 1);
 
   if (Value *V = ValuePtrs[Idx]) {
-    assert(Ty == V->getType() && "Type mismatch in constant table!");
+    if (Ty != V->getType())
+      report_fatal_error("Type mismatch in constant table!");
     return cast<Constant>(V);
   }