fix: only append type flag to curl if type is defined (via #5041)

* issue 5040: only append type to formData file if defined

* errant whitespace removal:

* conform to code style

* code style

* use template string in nested type ternary operator

src/core/curlify.js

@@ -23,7 +23,7 @@ export default function curl( request ){
       for( let [ k,v ] of request.get("body").entrySeq()) {
         curlified.push( "-F" )
         if (v instanceof win.File) {
-          curlified.push( `"${k}=@${v.name};type=${v.type}"` )
+          curlified.push( `"${k}=@${v.name}${v.type ? `;type=${v.type}` : ""}"` )
         } else {
           curlified.push( `"${k}=${v}"` )
         }

test/core/curlify.js

@@ -163,6 +163,26 @@ describe("curlify", function() {
         expect(curlified).toEqual("curl -X POST \"http://example.com\" -H  \"content-type: multipart/form-data\" -F \"id=123\" -F \"file=@file.txt;type=text/plain\"")
     })
 
+    it("should print a curl without form data type if type is unknown", function() {
+      var file = new win.File()
+      file.name = "file.txt"
+      file.type = ""
+
+      var req = {
+        url: "http://example.com",
+        method: "POST",
+        headers: { "content-type": "multipart/form-data" },
+        body: {
+          id: "123",
+          file
+        }
+      }
+
+      let curlified = curl(Im.fromJS(req))
+
+      expect(curlified).toEqual("curl -X POST \"http://example.com\" -H  \"content-type: multipart/form-data\" -F \"id=123\" -F \"file=@file.txt\"")
+    })
+
     it("prints a curl post statement from an object", function() {
         var req = {
             url: "http://example.com",