fix paste with new line

packages/altair-app/src/app/modules/altair/components/x-input/x-input.component.ts

@@ -15,7 +15,13 @@ import {
   CompletionContext,
   completionKeymap,
 } from '@codemirror/autocomplete';
-import { EditorState, Extension, StateEffect, StateField } from '@codemirror/state';
+import {
+  ChangeSpec,
+  EditorState,
+  Extension,
+  StateEffect,
+  StateField,
+} from '@codemirror/state';
 import {
   Decoration,
   DecorationSet,
@@ -126,8 +132,28 @@ export class XInputComponent implements AfterViewInit, ControlValueAccessor {
         },
       },
     });
+
     const filterNewLine = EditorState.transactionFilter.of((tr) => {
-      return tr.newDoc.lines > 1 ? [] : [tr];
+      if (tr.changes.empty) return tr;
+      if (tr.newDoc.lines > 1 && !tr.isUserEvent('input.paste')) {
+        return [];
+      }
+
+      const removeNLs: ChangeSpec[] = [];
+      tr.changes.iterChanges((fromA, toA, fromB, toB, ins) => {
+        const lineIter = ins.iterLines().next();
+        if (ins.lines <= 1) return;
+        // skip the first line
+        let len = fromB + lineIter.value.length;
+        lineIter.next();
+        // for the next lines, remove the leading NL
+        for (; !lineIter.done; lineIter.next()) {
+          removeNLs.push({ from: len, to: len + 1 });
+          len += lineIter.value.length + 1;
+        }
+      });
+
+      return [tr, { changes: removeNLs, sequential: true }];
     });
 
     return [