runtime error: invalid memory address or nil pointer dereference

[rollbar]

View details in Rollbar: https://rollbar.com/RTradeLtd/RTC-IPFS/items/8/

Traceback (most recent call last):
  File "/usr/local/go/src/runtime/panic.go", line 503, in runtime.gopanic
  File "/usr/local/go/src/runtime/panic.go", line 63, in runtime.panicmem
  File "/usr/local/go/src/runtime/signal_unix.go", line 388, in runtime.sigpanic
  File "/usr/local/go/src/mime/multipart/formdata.go", line 151, in multipart.(*FileHeader).Open
  File "github.com/RTradeLtd/RTC-IPFS/api/api.go", line 56, in api.addFile
  File "github.com/gin-gonic/gin/context.go", line 107, in gin.(*Context).Next
  File "github.com/gin-contrib/rollbar/recovey.go", line 40, in rollbar.Recovery.func1
  File "github.com/gin-gonic/gin/context.go", line 107, in gin.(*Context).Next
  File "github.com/gin-gonic/gin/recovery.go", line 48, in gin.RecoveryWithWriter.func1
  File "github.com/gin-gonic/gin/context.go", line 107, in gin.(*Context).Next
  File "github.com/gin-gonic/gin/logger.go", line 86, in gin.LoggerWithWriter.func1
  File "github.com/gin-gonic/gin/context.go", line 107, in gin.(*Context).Next
  File "github.com/gin-gonic/gin/gin.go", line 359, in gin.(*Engine).handleHTTPRequest
  File "github.com/gin-gonic/gin/gin.go", line 326, in gin.(*Engine).ServeHTTP
  File "/usr/local/go/src/net/http/server.go", line 2695, in http.serverHandler.ServeHTTP
  File "/usr/local/go/src/net/http/server.go", line 1830, in http.(*conn).serve
  File "/usr/local/go/src/runtime/asm_amd64.s", line 2362, in runtime.goexit
{1a5c186c}: runtime error: invalid memory address or nil pointer dereference