Crash in SetTag

[rjkroege]

Select a valid Edit command. M-L click on Edit.

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x2 addr=0x158 pc=0x102e55a7c]

goroutine 23 [running, locked to thread]:
main.(*Window).SetTag.func1({0x102ee31c0, 0x1400109c120})
	/Users/rjkroege/tools/edwood/wind.go:466 +0x3c
github.com/rjkroege/edwood/file.(*ObservableEditableBuffer).AllObservers(0x1400097f030, 0x102ee67b8)
	/Users/rjkroege/tools/edwood/file/observable_editable_buffer.go:102 +0x6c
main.(*Window).SetTag(0x14000298c00)
	/Users/rjkroege/tools/edwood/wind.go:464 +0x38
main.allupdate(0x14000298c00)
	/Users/rjkroege/tools/edwood/edit.go:196 +0xbc
main.(*Row).AllWindows(0x14000127598, 0x102ee6800)
	/Users/rjkroege/tools/edwood/row.go:643 +0x8c
main.editcmd(0x140013c2020, {0x1400011b5f0, 0xc, 0xc})
	/Users/rjkroege/tools/edwood/edit.go:237 +0x380
main.edit(0x140013c2020, 0x140013c2120, 0x140013c2120, 0x1, 0x1, {0x0, 0x0})
	/Users/rjkroege/tools/edwood/exec.go:240 +0x94
main.execute(0x140013c2020, 0x2c, 0x2c, 0x0, 0x140013c2120)
	/Users/rjkroege/tools/edwood/exec.go:219 +0xadc
main.MovedMouse(0x14000127500, {{0xf85, 0x53}, 0x2, 0xa72077cc})
	/Users/rjkroege/tools/edwood/acme.go:368 +0x638
main.mousethread(0x14000127500, {0x102eefdf8, 0x140001320a8})
	/Users/rjkroege/tools/edwood/acme.go:232 +0x224
created by main.main.func1
	/Users/rjkroege/tools/edwood/acme.go:139 +0x468