Small cleanups in SQL/JSON code

These are to keep Coverity happy. In one case remove a redundant NULL
check, and in another explicitly ignore a function result that is already
known.

Author: adunstan

src/backend/parser/parse_expr.c

@@ -3569,7 +3569,7 @@ coerceJsonFuncExpr(ParseState *pstate, Node *expr,
 	location = exprLocation(expr);
 
 	if (location < 0)
-		location = returning ? returning->format->location : -1;
+		location = returning->format->location;
 
 	/* special case for RETURNING bytea FORMAT json */
 	if (returning->format->format_type == JS_FORMAT_JSON &&

src/backend/utils/adt/jsonb.c

@@ -2264,7 +2264,7 @@ JsonbUnquote(Jsonb *jb)
 	{
 		JsonbValue	v;
 
-		JsonbExtractScalar(&jb->root, &v);
+		(void) JsonbExtractScalar(&jb->root, &v);
 
 		if (v.type == jbvString)
 			return pnstrdup(v.val.string.val, v.val.string.len);