[Verif][VerifyClockedAssertLike] Don't crash on blockarg operand.

lib/Dialect/Verif/Transforms/VerifyClockedAssertLike.cpp

@@ -56,6 +56,9 @@ private:
 
     Operation *property = clockedAssertLikeOp->getOperand(0).getDefiningOp();
 
+    if (!property)
+      return;
+
     // Fill in our worklist
     worklist.insert({property, property->operand_begin()});
 

test/Dialect/Verif/verify.mlir

@@ -44,3 +44,9 @@ hw.module @deeplynested(in %clk: i1, in %a: i1, in %b: i1) {
 
   verif.clocked_assert %o1 if %b, posedge %clk : !ltl.property
 }
+
+// -----
+
+hw.module @clockedarg(in %clocked: !ltl.property, in %a: i1, in %clk: i1) {
+  verif.clocked_assert %clocked if %a, posedge %clk : !ltl.property
+}