@uppy/form: migrate to TS

[Murderlon]

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[github-actions]

Diff output files

diff --git a/packages/@uppy/form/lib/index.js b/packages/@uppy/form/lib/index.js
index db0e390..a68da4d 100644
--- a/packages/@uppy/form/lib/index.js
+++ b/packages/@uppy/form/lib/index.js
@@ -5,25 +5,29 @@ import getFormData from "get-form-data";
 const packageJson = {
   "version": "3.1.1",
 };
+const defaultOptions = {
+  resultName: "uppyResult",
+  getMetaFromForm: true,
+  addResultToForm: true,
+  submitOnSuccess: false,
+  triggerUploadOnSubmit: false,
+};
+function assertHTMLFormElement(input) {
+  if (input == null || input.nodeName !== "FORM") {
+    throw new Error("ASSERTION FAILED: the target is not a <form> element", {
+      cause: input,
+    });
+  }
+  return input;
+}
 export default class Form extends BasePlugin {
   constructor(uppy, opts) {
-    super(uppy, opts);
-    this.form = void 0;
-    this.type = "acquirer";
-    this.id = this.opts.id || "Form";
-    this.title = "Form";
-    const defaultOptions = {
-      target: null,
-      resultName: "uppyResult",
-      getMetaFromForm: true,
-      addResultToForm: true,
-      submitOnSuccess: false,
-      triggerUploadOnSubmit: false,
-    };
-    this.opts = {
+    super(uppy, {
       ...defaultOptions,
       ...opts,
-    };
+    });
+    this.type = "acquirer";
+    this.id = this.opts.id || "Form";
     this.handleFormSubmit = this.handleFormSubmit.bind(this);
     this.handleUploadStart = this.handleUploadStart.bind(this);
     this.handleSuccess = this.handleSuccess.bind(this);
@@ -97,14 +101,7 @@ export default class Form extends BasePlugin {
     this.uppy.setMeta(formMeta);
   }
   install() {
-    this.form = findDOMElement(this.opts.target);
-    if (!this.form || this.form.nodeName !== "FORM") {
-      this.uppy.log(
-        "Form plugin requires a <form> target element passed in options to operate, none was found",
-        "error",
-      );
-      return;
-    }
+    this.form = assertHTMLFormElement(findDOMElement(this.opts.target));
     this.form.addEventListener("submit", this.handleFormSubmit);
     this.uppy.on("upload", this.handleUploadStart);
     this.uppy.on("complete", this.handleSuccess);