fix(emotion): use Buffer.from for base64 encoding in source maps

packages/emotion/src/source-map.test.ts

@@ -0,0 +1,29 @@
+import { describe, it, expect } from 'vitest'
+import { createSourceMap } from './source-map'
+
+describe('createSourceMap', () => {
+  it('handles source content with non-Latin-1 characters', () => {
+    // Regression: btoa() only supports Latin-1 (U+0000–U+00FF).
+    // Source files containing characters outside that range caused
+    // "Invalid character" errors when generating inline source maps.
+    const sourceWithUnicode = `
+      import { css } from '@emotion/react'
+      // Em dash: —
+      // Arrow: ➜
+      // Emoji: 🔁
+      const style = css\`color: red;\`
+    `
+    // With the old btoa() implementation, this would throw:
+    //   "Invalid character" at btoa (node:buffer)
+    expect(() =>
+      createSourceMap(sourceWithUnicode, 'test.tsx', { line: 6, column: 20 }),
+    ).not.toThrow()
+  })
+
+  it('returns a valid base64-encoded source map comment', () => {
+    const result = createSourceMap('const x = 1', 'test.tsx', { line: 0, column: 0 })
+    expect(result).toMatch(
+      /^\/\*# sourceMappingURL=data:application\/json;charset=utf-8;base64,[A-Za-z0-9+/=]+ \*\/$/,
+    )
+  })
+})

packages/emotion/src/source-map.ts

@@ -16,7 +16,7 @@ export function createSourceMap(
   setSourceContent(map, filename, sourceContent)
   addSegment(map, 0, 0, filename, pos.line, pos.column)
 
-  const encoded = btoa(JSON.stringify(toEncodedMap(map)))
+  const encoded = Buffer.from(JSON.stringify(toEncodedMap(map))).toString('base64')
   return `/*# sourceMappingURL=data:application/json;charset=utf-8;base64,${encoded} */`
 }