uniqueNames setting crashes generation for interface with empty field

System Information:

• Node - v14.15.4
• Typescript-json-schema version - 0.48.0
• OS: macOS 10.15.7 / Darwin 19.6.0
• Arch: x86_64

The file that I'm trying to parse is dead simple:

export interface RequestInterface {
    query: {
    }
}

The code that I'm trying to parse it with:

const typescript_json_schema_1 = require("typescript-json-schema");
const program = typescript_json_schema_1.getProgramFromFiles(['DeleteUser.ts'])
const generator = typescript_json_schema_1.buildGenerator(program, { required: true, uniqueNames: true });
const n = generator.getSymbols('RequestInterface')
generator.getSchemaForSymbol(n[0].name);

As you can see I'm just reading program, building generator and trying to get schema for my only interface. When launching, the app crashes with the following log:

Uncaught TypeError: Cannot read property 'length' of undefined
    at getCanonicalDeclaration (/Users/jbaramidze/playground/node_modules/typescript-json-schema/dist/typescript-json-schema.js:216:31)
    at getSourceFile (/Users/jbaramidze/playground/node_modules/typescript-json-schema/dist/typescript-json-schema.js:222:23)
    at JsonSchemaGenerator.getTypeDefinition (/Users/jbaramidze/playground/node_modules/typescript-json-schema/dist/typescript-json-schema.js:878:34)
    at JsonSchemaGenerator.getDefinitionForProperty (/Users/jbaramidze/playground/node_modules/typescript-json-schema/dist/typescript-json-schema.js:458:31)
    at /Users/jbaramidze/playground/node_modules/typescript-json-schema/dist/typescript-json-schema.js:752:37
    at Array.reduce (<anonymous>)
    at JsonSchemaGenerator.getClassDefinition (/Users/jbaramidze/playground/node_modules/typescript-json-schema/dist/typescript-json-schema.js:750:45)
    at JsonSchemaGenerator.getTypeDefinition (/Users/jbaramidze/playground/node_modules/typescript-json-schema/dist/typescript-json-schema.js:969:26)
    at JsonSchemaGenerator.getSchemaForSymbol (/Users/jbaramidze/playground/node_modules/typescript-json-schema/dist/typescript-json-schema.js:1000:24)

It works fine if I remove the uniqueNames: true setting. It also works fine if I add any member in query param.

P.S. It also crashes if I try to parse with CLI:

typescript-json-schema --uniqueNames DeleteUser.ts RequestInterface

Reproduce the crash with the shown RequestInterface and the uniqueNames option, then trace the reported path through dist/typescript-json-schema.js from getCanonicalDeclaration and getSourceFile into JsonSchemaGenerator.getTypeDefinition. Done means schema generation succeeds for an interface containing an empty query field, both through the API example and the --uniqueNames CLI invocation.