[HUDI-3847] Fix NPE due to null schema in HoodieMetadataTableValidator (#5284)

hudi-utilities/src/main/java/org/apache/hudi/utilities/HoodieMetadataTableValidator.java

@@ -68,6 +68,7 @@ import org.apache.hadoop.fs.Path;
 import org.apache.log4j.LogManager;
 import org.apache.log4j.Logger;
 import org.apache.parquet.avro.AvroSchemaConverter;
+import org.apache.parquet.schema.MessageType;
 import org.apache.spark.SparkConf;
 import org.apache.spark.api.java.JavaSparkContext;
 
@@ -808,9 +809,14 @@ public class HoodieMetadataTableValidator implements Serializable {
     for (String logFilePathStr : logFilePathSet) {
       HoodieLogFormat.Reader reader = null;
       try {
-        Schema readerSchema =
-            converter.convert(Objects.requireNonNull(
-                TableSchemaResolver.readSchemaFromLogFile(fs, new Path(logFilePathStr))));
+        MessageType messageType =
+            TableSchemaResolver.readSchemaFromLogFile(fs, new Path(logFilePathStr));
+        if (messageType == null) {
+          LOG.warn(String.format("Cannot read schema from log file %s. "
+              + "Skip the check as it's likely being written by an inflight instant.", logFilePathStr));
+          continue;
+        }
+        Schema readerSchema = converter.convert(messageType);
         reader =
             HoodieLogFormat.newReader(fs, new HoodieLogFile(new Path(logFilePathStr)), readerSchema);
         // read the avro blocks
@@ -829,7 +835,9 @@ public class HoodieMetadataTableValidator implements Serializable {
           LOG.warn("There is no log block in " + logFilePathStr);
         }
       } catch (IOException e) {
-        throw new HoodieValidationException("Validation failed due to IOException", e);
+        LOG.warn(String.format("Cannot read log file %s: %s. "
+                + "Skip the check as it's likely being written by an inflight instant.",
+            logFilePathStr, e.getMessage()), e);
       } finally {
         FileIOUtils.closeQuietly(reader);
       }