@webdoc/parser 1.6.0 crashes when mangling a method with no parameter

[Julien-Marcou]

Related to pixijs/pixijs#8480

When @webdoc/parser parses a method that has no parameters, it crashes with the following error:

(node:4199) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'map' of undefined
    at mangled (/home/runner/work/pixijs/pixijs/node_modules/@webdoc/model/lib/doc.js:296:50)
    at discoverMembers (/home/runner/work/pixijs/pixijs/node_modules/@webdoc/parser/lib/transformer/mod-discover-members.js:53:45)
    at ensureDiscovered (/home/runner/work/pixijs/pixijs/node_modules/@webdoc/parser/lib/transformer/mod-discover-members.js:21:3)
    at discoverMembers (/home/runner/work/pixijs/pixijs/node_modules/@webdoc/parser/lib/transformer/mod-discover-members.js:81:5)
    at discover (/home/runner/work/pixijs/pixijs/node_modules/@webdoc/parser/lib/transformer/mod-discover-members.js:116:3)
    at Object.discover [as mod] (/home/runner/work/pixijs/pixijs/node_modules/@webdoc/parser/lib/transformer/mod-discover-members.js:120:7)
    at mod (/home/runner/work/pixijs/pixijs/node_modules/@webdoc/parser/lib/transformer/document-tree-modifiers.js:66:22)
    at parse (/home/runner/work/pixijs/pixijs/node_modules/@webdoc/parser/lib/parse.js:82:38)
    at async main (/home/runner/work/pixijs/pixijs/node_modules/@webdoc/cli/lib/index.js:136:5)

The mangled() function doesn't check if params is defined, it should probably return something like ${doc.type}:${doc.name} or ${doc.type}:${doc.name}:undefined when that is the case:

webdoc/packages/webdoc-model/src/doc.js

Lines 356 to 363 in b7cf3dd

	export function mangled(doc: Doc): string {
	if (doc.type === "MethodDoc") {
	return `${doc.type}:${doc.name}:${
	doc.params.map((p) => p.dataType ? p.dataType[0] : "unknown").join("-")}`;
	}
	return `${doc.type}:${doc.name}`;
	}

[ShukantPal]

It fails here: https://github.com/pixijs/pixijs/blob/9b724f289118ebbf9b4500fa3faab1e7aaaabd02/packages/display/src/DisplayObject.ts#L324