by bcwaldon:

What does 'go version' print?

go version go1.2.1 darwin/amd64

What steps reproduce the problem?

```
package main

import (
        "fmt"
        "os"
        "text/tabwriter"
)

func main() {
        writer := new(tabwriter.Writer)
        writer.Init(os.Stdout, 0, 8, 1, '\t', 0)

        count := 100000

        start := make(chan bool)
        done := make(chan bool, count)

        write := func(msg string) {
                <-start
                fmt.Fprintln(writer, msg)
                done <- true
        }

        for i := 0; i < count; i++ {
                go write("foo")
        }

        close(start)

        for i := 0; i < count; i++ {
                <-done
        }
}
```

What happened?

panic: runtime error: index out of range [recovered]
        panic: interface conversion: interface is runtime.errorCString, not tabwriter.osError [recovered]
        panic: interface conversion: interface is *runtime.TypeAssertionError, not tabwriter.osError

goroutine 33040 [running]:
runtime.panic(0xa64a0, 0x210266080)
        /usr/local/Cellar/go/1.2.1/libexec/src/pkg/runtime/panic.c:266 +0xb6
text/tabwriter.handlePanic(0x2220732ee0)
        /usr/local/Cellar/go/1.2.1/libexec/src/pkg/text/tabwriter/tabwriter.go:439 +0x4e
runtime.panic(0xa64a0, 0x210266040)
        /usr/local/Cellar/go/1.2.1/libexec/src/pkg/runtime/panic.c:248 +0x106
text/tabwriter.handlePanic(0x2220732df0)
        /usr/local/Cellar/go/1.2.1/libexec/src/pkg/text/tabwriter/tabwriter.go:439 +0x4e
runtime.panic(0xa6180, 0x18fed7)
        /usr/local/Cellar/go/1.2.1/libexec/src/pkg/runtime/panic.c:248 +0x106
text/tabwriter.(*Writer).writeLines(0x210269000, 0x0, 0x0, 0x5, 0x3)
        /usr/local/Cellar/go/1.2.1/libexec/src/pkg/text/tabwriter/tabwriter.go:262 +0x5b3
text/tabwriter.(*Writer).format(0x210269000, 0x0, 0x0, 0x5, 0x5)
        /usr/local/Cellar/go/1.2.1/libexec/src/pkg/text/tabwriter/tabwriter.go:370 +0x307
text/tabwriter.(*Writer).Flush(0x210269000, 0x0, 0x0)
        /usr/local/Cellar/go/1.2.1/libexec/src/pkg/text/tabwriter/tabwriter.go:462 +0xce
text/tabwriter.(*Writer).Write(0x210269000, 0x210222068, 0x4, 0x6, 0x4, ...)
        /usr/local/Cellar/go/1.2.1/libexec/src/pkg/text/tabwriter/tabwriter.go:497 +0x3e9
fmt.Fprintln(0x2239f51640, 0x210269000, 0x2220732f60, 0x1, 0x1, ...)
        /usr/local/Cellar/go/1.2.1/libexec/src/pkg/fmt/print.go:287 +0xa3
main.func·001(0xbcfc0, 0x3)
        /private/tmp/tabwriter.go:20 +0x11a
created by main.main
        /private/tmp/tabwriter.go:25 +0x19d


What should have happened instead?

No panic.

Please provide any additional information below.

This panic is not encountered every time I run the script.