### What changes were proposed in this pull request?
In the PR, I propose to restrict the partial result feature only by root JSON objects. JSON datasource as well as `from_json()` will return `null` for malformed nested JSON objects.
### Why are the changes needed?
1. To not raise exception to users in the PERMISSIVE mode
2. To fix a regression and to have the same behavior as Spark 2.4.x has
3. Current implementation of partial result is supposed to work only for root (top-level) JSON objects, and not tested for bad nested complex JSON fields.
### Does this PR introduce _any_ user-facing change?
Yes. Before the changes, the code below:
```scala
val pokerhand_raw = Seq("""[{"cards": [19], "playerId": 123456}]""").toDF("events")
val event = new StructType().add("playerId", LongType).add("cards", ArrayType(new StructType().add("id", LongType).add("rank", StringType)))
val pokerhand_events = pokerhand_raw.select(from_json($"events", ArrayType(event)).as("event"))
pokerhand_events.show
```
throws the exception even in the default **PERMISSIVE** mode:
```java
java.lang.ClassCastException: java.lang.Long cannot be cast to org.apache.spark.sql.catalyst.util.ArrayData
at org.apache.spark.sql.catalyst.expressions.BaseGenericInternalRow.getArray(rows.scala:48)
at org.apache.spark.sql.catalyst.expressions.BaseGenericInternalRow.getArray$(rows.scala:48)
at org.apache.spark.sql.catalyst.expressions.GenericInternalRow.getArray(rows.scala:195)
```
After the changes:
```
+-----+
|event|
+-----+
| null|
+-----+
```
### How was this patch tested?
Added a test to `JsonFunctionsSuite`.
Closes#30031 from MaxGekk/json-skip-row-wrong-schema.
Authored-by: Max Gekk <max.gekk@gmail.com>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>
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