Add expected mapping type to MapperException (#31564)

Currently if a document cannot be indexed because it violates the defined 
mapping for the index, a MapperException is thrown. In some cases it is 
useful to expose the expected field type in the exception itself, 
so that the user can react based on the error message. This change adds 
the expected data type to the MapperException.

Closes #31502

Author: lipsill

server/src/main/java/org/elasticsearch/index/mapper/FieldMapper.java

@@ -299,7 +299,8 @@ public Mapper parse(ParseContext context) throws IOException {
                 context.doc().add(field);
             }
         } catch (Exception e) {
-            throw new MapperParsingException("failed to parse [" + fieldType().name() + "]", e);
+            throw new MapperParsingException("failed to parse field [{}] of type [{}]", e, fieldType().name(),
+                    fieldType().typeName());
         }
         multiFields.parse(this, context);
         return null;

server/src/main/java/org/elasticsearch/index/mapper/GeoShapeFieldMapper.java

@@ -519,7 +519,8 @@ public Mapper parse(ParseContext context) throws IOException {
             indexShape(context, shape);
         } catch (Exception e) {
             if (ignoreMalformed.value() == false) {
-                throw new MapperParsingException("failed to parse [" + fieldType().name() + "]", e);
+                throw new MapperParsingException("failed to parse field [{}] of type [{}]", e, fieldType().name(),
+                        fieldType().typeName());
             }
             context.addIgnoredField(fieldType.name());
         }

server/src/test/java/org/elasticsearch/index/mapper/BooleanFieldMapperTests.java

@@ -196,7 +196,7 @@ public void testParsesEs6BooleansStrict() throws IOException {
                 .endObject());
         MapperParsingException ex = expectThrows(MapperParsingException.class,
                 () -> defaultMapper.parse(SourceToParse.source("test", "type", "1", source, XContentType.JSON)));
-        assertEquals("failed to parse [field]", ex.getMessage());
+        assertEquals("failed to parse field [field] of type [boolean]", ex.getMessage());
     }
 
     public void testMultiFields() throws IOException {

server/src/test/java/org/elasticsearch/index/mapper/DocumentParserTests.java

@@ -125,6 +125,35 @@ public void testDotsWithExistingNestedMapper() throws Exception {
                 e.getMessage());
     }
 
+    public void testUnexpectedFieldMappingType() throws Exception {
+        DocumentMapperParser mapperParser = createIndex("test").mapperService().documentMapperParser();
+        String mapping = Strings.toString(XContentFactory.jsonBuilder().startObject().startObject("type").startObject("properties")
+                .startObject("foo").field("type", "long").endObject()
+                .startObject("bar").field("type", "boolean").endObject()
+                .startObject("geo").field("type", "geo_shape").endObject()
+                .endObject().endObject().endObject());
+        DocumentMapper mapper = mapperParser.parse("type", new CompressedXContent(mapping));
+        {
+            BytesReference bytes = BytesReference.bytes(XContentFactory.jsonBuilder().startObject().field("foo", true).endObject());
+            MapperException exception = expectThrows(MapperException.class,
+                    () -> mapper.parse(SourceToParse.source("test", "type", "1", bytes, XContentType.JSON)));
+            assertThat(exception.getMessage(), containsString("failed to parse field [foo] of type [long]"));
+        }
+        {
+            BytesReference bytes = BytesReference.bytes(XContentFactory.jsonBuilder().startObject().field("bar", "bar").endObject());
+            MapperException exception = expectThrows(MapperException.class,
+                    () -> mapper.parse(SourceToParse.source("test", "type", "2", bytes, XContentType.JSON)));
+            assertThat(exception.getMessage(), containsString("failed to parse field [bar] of type [boolean]"));
+        }
+        {
+            BytesReference bytes = BytesReference.bytes(XContentFactory.jsonBuilder().startObject().field("geo", 123).endObject());
+            MapperException exception = expectThrows(MapperException.class,
+                    () -> mapper.parse(SourceToParse.source("test", "type", "2", bytes, XContentType.JSON)));
+            assertThat(exception.getMessage(), containsString("failed to parse field [geo] of type [geo_shape]"));
+        }
+
+    }
+
     public void testDotsWithDynamicNestedMapper() throws Exception {
         DocumentMapperParser mapperParser = createIndex("test").mapperService().documentMapperParser();
         String mapping = Strings.toString(XContentFactory.jsonBuilder().startObject().startObject("type")