fix: fix incorrect nil return value (#1630)

## Description

Since we have already checked err before and returned != nil, err must
be nil here. In fact, it should return `err2 `.

Signed-off-by: huochexizhan <[email protected]>

Author: huochexizhan

app/query.go

@@ -441,7 +441,7 @@ func (app PocketCoreApp) QueryParam(height int64, paramkey string) (r SinglePara
 		if err2 != nil {
 			//ignoring this error as content is a json object
 			r.Value = val
-			return r, err
+			return r, err2
 		}
 		r.Value = s
 	}