ALE stops working on save in Go buffer

**VIM Version (Neovim)**
```
NVIM v0.3.4
Build type: Release
LuaJIT 2.0.5
Compilation: /usr/bin/cc -march=x86-64 -mtune=generic -O2 -pipe -fstack-protector-strong -fno-plt -Wconversion -O2 -DNDEBUG -DMIN_LOG_LEVEL=3 -Wall -Wextra -pedantic -Wno-unused-parameter -Wstrict-prototypes -std=gnu99 -Wimplicit-fallthrough -Wvla -fstack-protector-strong -fdiagnostics-color=auto -Wno-array-bounds -DINCLUDE_GENERATED_DECLARATIONS -D_GNU_SOURCE -DNVIM_MSGPACK_HAS_FLOAT32 -DNVIM_UNIBI_HAS_VAR_FROM -I/build/neovim/src/build/config -I/build/neovim/src/neovim-0.3.4/src -I/usr/include -I/build/neovim/src/build/src/nvim/auto -I/build/neovim/src/build/include
Compiled by builduser

Features: +acl +iconv +jemalloc +tui
```

**OS**
```
Linux hydrogen 5.0.3-arch1-1-ARCH #1 SMP PREEMPT Tue Mar 19 13:09:13 UTC 2019 x86_64 GNU/Linux
```

**:ALEInfo**
```
Current Filetype: go
Available Linters: ['bingo', 'gobuild', 'gofmt', 'golangci-lint', 'golint', 'gometalinter', 'gosimple', 'gotype', 'govet', 'golangserver', 'staticcheck']
Linter Aliases:
'gobuild' -> ['go build']
'govet' -> ['go vet']
Enabled Linters: ['gofmt', 'govet', 'golangserver']
Suggested Fixers:
'gofmt' - Fix Go files with go fmt.
'goimports' - Fix Go files imports with goimports.
'remove_trailing_lines' - Remove all blank lines at the end of a file.
'trim_whitespace' - Remove all trailing whitespace characters at the end of every line.
Linter Variables:

let g:ale_go_govet_options = ''
Global Variables:

let g:ale_cache_executable_check_failures = v:null
let g:ale_change_sign_column_color = 0
let g:ale_command_wrapper = ''
let g:ale_completion_delay = 100
let g:ale_completion_enabled = 1
let g:ale_completion_max_suggestions = 50
let g:ale_echo_cursor = 1
let g:ale_echo_msg_error_str = 'Error'
let g:ale_echo_msg_format = '%code: %%s'
let g:ale_echo_msg_info_str = 'Info'
let g:ale_echo_msg_warning_str = 'Warning'
let g:ale_enabled = 1
let g:ale_fix_on_save = 0
let g:ale_fixers = {}
let g:ale_history_enabled = 1
let g:ale_history_log_output = 1
let g:ale_keep_list_window_open = 0
let g:ale_lint_delay = 200
let g:ale_lint_on_enter = 1
let g:ale_lint_on_filetype_changed = 1
let g:ale_lint_on_insert_leave = 0
let g:ale_lint_on_save = 1
let g:ale_lint_on_text_changed = 'always'
let g:ale_linter_aliases = {}
let g:ale_linters = {'go': ['gofmt', 'govet', 'golangserver']}
let g:ale_linters_explicit = 0
let g:ale_list_vertical = 0
let g:ale_list_window_size = 10
let g:ale_loclist_msg_format = '%code: %%s'
let g:ale_lsp_root = {}
let g:ale_max_buffer_history_size = 20
let g:ale_max_signs = -1
let g:ale_maximum_file_size = v:null
let g:ale_open_list = 0
let g:ale_pattern_options = v:null
let g:ale_pattern_options_enabled = v:null
let g:ale_set_balloons = 0
let g:ale_set_highlights = 1
let g:ale_set_loclist = 1
let g:ale_set_quickfix = 0
let g:ale_set_signs = 1
let g:ale_sign_column_always = 0
let g:ale_sign_error = '>>'
let g:ale_sign_info = '--'
let g:ale_sign_offset = 1000000
let g:ale_sign_style_error = '>>'
let g:ale_sign_style_warning = '--'
let g:ale_sign_warning = '--'
let g:ale_statusline_format = v:null
let g:ale_type_map = {}
let g:ale_use_global_executables = v:null
let g:ale_virtualtext_cursor = 0
let g:ale_warn_about_trailing_blank_lines = 1
let g:ale_warn_about_trailing_whitespace = 1
```

**Error**
When I have following code in Go:
```go
func foo() (string, error) {
return nil,
}
```
and save the file with `:w`, it throws an error like this and gofmt stops working:
```
Error detected while processing function 193[2]..194[4]..204:
line 5:
E788: Not allowed to edit another buffer now
Press ENTER or type command to continue
```

I think this is related to `ALE`, since removing `ALE` will not reproduce the issue.
I'm not certain if it's an issue with `gofmt`, `govet`.

Start by reproducing the reported save failure in a Go buffer with the listed ALE linters enabled, then compare whether gofmt, govet, or their interaction triggers E788. Done means saving no longer reports “Not allowed to edit another buffer now” and gofmt continues to work.

Written by the indexing model from the issue text.