nulls.Int quietly disregards bad data

[nscharfe]

Description

A couple things I noticed when calling c.Bind in actions handlers:

• Unexpected data types can cause panics
• Unexpected data types can cause data to be silently discarded

Steps to Reproduce the Problem

Using buffalo in api mode. A simplified example:
I have a model defined like this:

type MyModel struct {
  ID                      uuid.UUID
  MyFloatField            nulls.Float
  MyIntField              nulls.Int
}

My create handler has the following lines in it:

...
myModel := &models.MyModel{}
if err := c.Bind(myModel); err != nil {
    return errors.WithStack(err)
}
...

Issue 1:

• I post {"my_float_field": "5.5"} to /create => I get a 500 and it seems that c.Bind is panicking internally (It is expecting a float and gets a string). I would expect c.Bind to return an error so that I can handle it gracefully rather than panic / 500.
• I post ``{"my_int_field": "5.5"} to /create => binding silently discards `my_int_field` value and the struct field values are all null after binding, no error is returned

Expected Behavior

Expect to get error returned in this case rather than a panic and/or silent loss of data

Info

### Buffalo Version
v0.13.12

### App Information
Pwd=/Users/dev/go/src/github.com/af/institutional-api
Root=/Users/dev/go/src/github.com/af/institutional-api
GoPath=/Users/dev/go
Name=institutional-api
Bin=bin/institutional-api
PackagePkg=github.com/af/institutional-api
ActionsPkg=github.com/af/institutional-api/actions
ModelsPkg=github.com/af/institutional-api/models
GriftsPkg=github.com/af/institutional-api/grifts
VCS=git
WithPop=true
WithSQLite=false
WithDep=true
WithWebpack=false
WithYarn=false
WithDocker=true
WithGrifts=true
WithModules=false

### Go Version
go version go1.11.2 darwin/amd64

### Go Env
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/nscharfe/Library/Caches/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/nscharfe/go"
GOPROXY=""
GORACE=""
GOROOT="/usr/local/go"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/st/nhlg61pn5_s7m6v7by0wjmtc0000gn/T/go-build752508143=/tmp/go-build -gno-record-gcc-switches -fno-common"

### Node Version
v6.0.0

### NPM Version
3.8.6

### Yarn Version
1.9.4

### PostgreSQL Version
pg_ctl (PostgreSQL) 10.5

### MySQL Version
MySQL Not Found

### SQLite Version
3.24.0 2018-06-04 14:10:15 95fbac39baaab1c3a84fdfc82ccb7f42398b2e92f18a2a57bce1d4a713cbaapl

### Dep Version
dep:
 version     : devel
 build date  : 
 git hash    : 
 go version  : go1.11.2
 go compiler : gc
 platform    : darwin/amd64
 features    : ImportDuringSolve=false

[markbates]

I'm not able to get a panic when trying to test this in v0.14.0.beta2:

type badActor struct {
	A float64
	B int
}

func Test_Exec_Bad_Actors(t *testing.T) {
	r := require.New(t)
	rd := strings.NewReader(`{"A": "5.5", "B": "adsf"}`)
	req := httptest.NewRequest("POST", "/", rd)
	req.Header.Set("Content-Type", "application/json")
	a := &badActor{}
	err := Exec(req, a)
	r.Error(err)
}

The error returned is json: cannot unmarshal string into Go struct field badActor.A of type float64.

When I try to use nulls.Float64 instead of a standard float64, I get strconv.ParseFloat: parsing "\"5.5\"": invalid syntax

The only thing I can confirm is that nulls.Int seems to be throwing away bad data. I'm going to transfer this issue to that package, as I can't get buffalo to reproduce the panic's, but I can reproduce the issue with nulls.Int.