Java: Catch NPE if the type isn't set

core/src/main/java/org/apache/iceberg/SchemaParser.java

@@ -183,13 +183,16 @@ private static Type typeFromJson(JsonNode json) {
       return Types.fromPrimitiveString(json.asText());
 
     } else if (json.isObject()) {
-      String type = json.get(TYPE).asText();
-      if (STRUCT.equals(type)) {
-        return structFromJson(json);
-      } else if (LIST.equals(type)) {
-        return listFromJson(json);
-      } else if (MAP.equals(type)) {
-        return mapFromJson(json);
+      JsonNode typeObj = json.get(TYPE);
+      if (typeObj != null) {
+        String type =  typeObj.asText();
+        if (STRUCT.equals(type)) {
+          return structFromJson(json);
+        } else if (LIST.equals(type)) {
+          return listFromJson(json);
+        } else if (MAP.equals(type)) {
+          return mapFromJson(json);
+        }
       }
     }
 
@@ -254,7 +257,7 @@ private static Types.MapType mapFromJson(JsonNode json) {
   }
 
   public static Schema fromJson(JsonNode json) {
-    Type type  = typeFromJson(json);
+    Type type = typeFromJson(json);
     Preconditions.checkArgument(type.isNestedType() && type.asNestedType().isStructType(),
         "Cannot create schema, not a struct type: %s", type);
     Integer schemaId = JsonUtil.getIntOrNull(SCHEMA_ID, json);

core/src/test/java/org/apache/iceberg/rest/responses/TestLoadTableResponse.java

@@ -120,6 +120,18 @@ public void testRoundTripSerdeWithV1TableMetadata() throws Exception {
     assertRoundTripSerializesEquallyFrom(json, resp);
   }
 
+  @Test
+  public void testMissingSchemaType() throws Exception {
+    // When the schema type (struct) is missing
+    String tableMetadataJson = readTableMetadataInputFile("TableMetadataV1MissingSchemaType.json");
+    AssertHelpers.assertThrows(
+        "Cannot parse type from json when there is no type",
+        IllegalArgumentException.class,
+        "Cannot parse type from json:",
+        () -> TableMetadataParser.fromJson(null, TEST_METADATA_LOCATION, tableMetadataJson)
+    );
+  }
+
   @Test
   public void testRoundTripSerdeWithV2TableMetadata() throws Exception {
     String tableMetadataJson = readTableMetadataInputFile("TableMetadataV2Valid.json");

core/src/test/resources/TableMetadataV1MissingSchemaType.json

@@ -0,0 +1,41 @@
+{
+  "format-version": 1,
+  "table-uuid": "d20125c8-7284-442c-9aea-15fee620737c",
+  "location": "s3://bucket/test/location",
+  "last-updated-ms": 1602638573874,
+  "last-column-id": 3,
+  "schema": {
+    "fields": [
+      {
+        "id": 1,
+        "name": "x",
+        "required": true,
+        "type": "long"
+      },
+      {
+        "id": 2,
+        "name": "y",
+        "required": true,
+        "type": "long",
+        "doc": "comment"
+      },
+      {
+        "id": 3,
+        "name": "z",
+        "required": true,
+        "type": "long"
+      }
+    ]
+  },
+  "partition-spec": [
+    {
+      "name": "x",
+      "transform": "identity",
+      "source-id": 1,
+      "field-id": 1000
+    }
+  ],
+  "properties": {},
+  "current-snapshot-id": -1,
+  "snapshots": []
+}