Updating error message for runtime and multi field type parser

Author: Samiul-TheSoccerFan

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

@@ -179,7 +179,11 @@ static Map<String, RuntimeField> parseRuntimeFields(
                 }
                 Parser typeParser = parserContext.runtimeFieldParser(type);
                 if (typeParser == null) {
-                    throw new MapperParsingException("No handler for type [" + type + "] declared on runtime field [" + fieldName + "]");
+                    throw new MapperParsingException(
+                        "The mapper type [" + type + "] declared on field [" + fieldName + "] does not exist."
+                            +   " It might have been created within a future version or requires a plugin to be installed."
+                            +   " Check the documentation."
+                    );
                 }
                 runtimeFields.put(fieldName, builder.apply(typeParser.parse(fieldName, propNode, parserContext)));
                 propNode.remove("type");

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

@@ -161,7 +161,11 @@ public static boolean parseMultiField(
 
                 Mapper.TypeParser typeParser = parserContext.typeParser(type);
                 if (typeParser == null) {
-                    throw new MapperParsingException("no handler for type [" + type + "] declared on field [" + multiFieldName + "]");
+                    throw new MapperParsingException(
+                        "The mapper type [" + type + "] declared on field [" + multiFieldName + "] does not exist."
+                            +   " It might have been created within a future version or requires a plugin to be installed."
+                            +   " Check the documentation."
+                    );
                 }
                 if (typeParser instanceof FieldMapper.TypeParser == false) {
                     throw new MapperParsingException("Type [" + type + "] cannot be used in multi field");

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

@@ -313,13 +313,19 @@ public void testRuntimeSectionMerge() throws IOException {
     public void testRuntimeSectionNonRuntimeType() throws IOException {
         XContentBuilder mapping = runtimeFieldMapping(builder -> builder.field("type", "unknown"));
         MapperParsingException e = expectThrows(MapperParsingException.class, () -> createMapperService(mapping));
-        assertEquals("Failed to parse mapping: No handler for type [unknown] declared on runtime field [field]", e.getMessage());
+        assertEquals("Failed to parse mapping: The mapper type [unknown] declared on field [field] does not exist."
+            + " It might have been created within a future version or requires a plugin to be installed. Check the documentation.",
+            e.getMessage()
+        );
     }
 
     public void testRuntimeSectionHandlerNotFound() throws IOException {
         XContentBuilder mapping = runtimeFieldMapping(builder -> builder.field("type", "unknown"));
         MapperParsingException e = expectThrows(MapperParsingException.class, () -> createMapperService(mapping));
-        assertEquals("Failed to parse mapping: No handler for type [unknown] declared on runtime field [field]", e.getMessage());
+        assertEquals("Failed to parse mapping: The mapper type [unknown] declared on field [field] does not exist."
+                + " It might have been created within a future version or requires a plugin to be installed. Check the documentation.",
+            e.getMessage()
+        );
     }
 
     public void testRuntimeSectionMissingType() throws IOException {