Update.

test/io/stdin/read_byte_closed.wren

@@ -0,0 +1,10 @@
+// retoor <retoor@molodetz.nl>
+
+import "io" for Stdin
+
+var fiber = Fiber.new {
+  Stdin.readByte()
+}
+
+var result = fiber.try()
+System.print(fiber.error) // expect: Stdin was closed.

test/io/stdin/read_line_closed.wren

@@ -0,0 +1,10 @@
+// retoor <retoor@molodetz.nl>
+
+import "io" for Stdin
+
+var fiber = Fiber.new {
+  Stdin.readLine()
+}
+
+var result = fiber.try()
+System.print(fiber.error) // expect: Stdin was closed.