Don't exit markup when there's content after the cursor

FIX: `insertNewlineContinueMarkup` will no longer exit lists when there is content
after the cursor.

See https://discuss.codemirror.net/t/bug-with-markdown-command/3794

src/commands.ts

@@ -102,7 +102,7 @@ export const insertNewlineContinueMarkup: StateCommand = ({state, dispatch}) =>
     if (inner.to - inner.spaceAfter.length > pos - line.from) return dont = {range}
 
     // Empty line in list
-    if (inner.item && pos >= (inner.to - inner.spaceAfter.length) && !/\S/.test(line.text.slice(inner.to, pos - line.from))) {
+    if (inner.item && pos >= (inner.to - inner.spaceAfter.length) && !/\S/.test(line.text.slice(inner.to))) {
       // First list item or blank line before: delete a level of markup
       if (inner.node.firstChild!.to >= pos ||
           line.from > 0 && !/[^\s>]/.test(doc.lineAt(line.from - 1).text)) {

test/test-commands.ts

@@ -86,9 +86,6 @@ describe("insertNewlineContinueMarkup", () => {
     test(" - one\n\n - |", " - one\n\n|")
   })
 
-  it("can drop list markup even with text after it", () =>
-    test(" - one\n - |two", " - one\n\n - |two"))
-
   it("deletes the first list marker", () =>
     test(" - |", "|"))
 
@@ -118,6 +115,11 @@ describe("insertNewlineContinueMarkup", () => {
 
   it("can lift out of one list level and renumber", () =>
     test("1. a\n\n   1. b\n\n   2. |\n\n2. d", "1. a\n\n   1. b\n\n2. |\n\n3. d"))
+
+  it("doesn't treat lines with content after the cursor as empty", () => {
+    test("1. |x\n2. y", "1.\n2. |x\n3. y")
+    test("1. x\n2. |y", "1. x\n2.\n3. |y")
+  })
 })
 
 describe("deleteMarkupBackward", () => {