[test] Unify the trap message of "null function reference".

Signed-off-by: YiYing He <[email protected]>

Author: q82419

test/core/call_ref.wast

@@ -94,7 +94,7 @@
 (assert_return (invoke "run" (i32.const 0)) (i32.const 0))
 (assert_return (invoke "run" (i32.const 3)) (i32.const -9))
 
-(assert_trap (invoke "null") "null function")
+(assert_trap (invoke "null") "null function reference")
 
 (assert_return (invoke "fac" (i64.const 0)) (i64.const 1))
 (assert_return (invoke "fac" (i64.const 1)) (i64.const 1))

test/core/return_call_ref.wast

@@ -180,7 +180,7 @@
 (assert_return (invoke "type-second-f32") (f32.const 32))
 (assert_return (invoke "type-second-f64") (f64.const 64.1))
 
-(assert_trap (invoke "null") "null function")
+(assert_trap (invoke "null") "null function reference")
 
 (assert_return (invoke "fac-acc" (i64.const 0) (i64.const 1)) (i64.const 1))
 (assert_return (invoke "fac-acc" (i64.const 1) (i64.const 1)) (i64.const 1))