[PANIC] Index out of range

[IGLOU-EU]

Hi, I have an index out of range with gofpdf@v1.4.2

panic: runtime error: index out of range [53] with length 0
goroutine 66 [running]:
github.com/phpdave11/gofpdf.(*Fpdf).write(0xc0003ac000, 0x4020000000000000, {0xc0004eaf00?, 0x4?}, 0x4?, {0x0, 0x0})
         /root/go/pkg/mod/github.com/phpdave11/gofpdf@v1.4.2/fpdf.go:2839 +0xbea
github.com/phpdave11/gofpdf.(*Fpdf).Write(...)
         /root/go/pkg/mod/github.com/phpdave11/gofpdf@v1.4.2/fpdf.go:2901
[...]

There is happening after a call to Write.
Used font are UbuntuFont

strBuff = fmt.Sprintf(
    "\n%s, %s, %s %s\n", 
    data.Simple["se-addr-num"], 
    data.Simple["se-addr-complement"], 
    data.Simple["se-addr-code"], 
    data.Simple["se-addr-commune"],
)

log.Println("DEBUG PANIC: ", strBuff)
pdf.Write(8, strBuff)

🤔

[IGLOU-EU]

This happens when we try to write without a loaded font.

My font isn't loaded because I haven't called "SetFontLocation", I'm pointing directly to the root path.
This problem happens here:

gofpdf/fpdf.go

Line 74 in b09d921

fontDirStr = "."

gofpdf/fpdf.go

Line 114 in b09d921

f.fontpath = fontDirStr

gofpdf/fpdf.go

Line 1687 in b09d921

fileStr = path.Join(f.fontpath, fileStr)

The behavior of path.Join' used with '.' is to remove the '/' if the target has one. Ex path.Join(".", "/tata/titi/toto.ttf")` = "tata/titi/toto.ttf"

To solve this issue:

• Change the magic value of fontDirStr
• Check if a font is loaded instead of panic

I planned to make a PR, what do you think about?