@uppy/core: check capabilities in clearUploadedFiles

[Murderlon]

Found out while working on #5158 that we block removeFiles during on upload if capabilities.individualCancellation is false but we blindly allow it in clearUploadedFiles.

[github-actions]

Diff output files

diff --git a/packages/@uppy/core/lib/Uppy.js b/packages/@uppy/core/lib/Uppy.js
index 6036373..953e090 100644
--- a/packages/@uppy/core/lib/Uppy.js
+++ b/packages/@uppy/core/lib/Uppy.js
@@ -331,6 +331,13 @@ export class Uppy {
     this.emit("reset-progress");
   }
   clearUploadedFiles() {
+    const {
+      capabilities,
+      currentUploads,
+    } = this.getState();
+    if (Object.keys(currentUploads).length > 0 && !capabilities.individualCancellation) {
+      throw new Error("The installed uploader plugin does not allow removing files during an upload.");
+    }
     this.setState({
       ...defaultUploadState,
       files: {},
@@ -600,7 +607,7 @@ export class Uppy {
         capabilities,
       } = this.getState();
       if (newFileIDs.length !== currentUploads[uploadID].fileIDs.length && !capabilities.individualCancellation) {
-        throw new Error("individualCancellation is disabled");
+        throw new Error("The installed uploader plugin does not allow removing files during an upload.");
       }
       updatedUploads[uploadID] = {
         ...currentUploads[uploadID],

[aduh95]

I guess it would be nice to have more DRY code to avoid this happening again, but the change LGTM nonetheless