vendor: update github.com/t3rm1n4l/go-mega and dependencies

This is to fix a crash reported in #3140

vendor/golang.org/x/text/unicode/bidi/bracket.go

@@ -246,7 +246,7 @@ func (p *bracketPairer) getStrongTypeN0(index int) Class {
 // assuming the given embedding direction.
 //
 // It returns ON if no strong type is found. If a single strong type is found,
-// it returns this this type. Otherwise it returns the embedding direction.
+// it returns this type. Otherwise it returns the embedding direction.
 //
 // TODO: use separate type for "strong" directionality.
 func (p *bracketPairer) classifyPairContent(loc bracketPair, dirEmbed Class) Class {

vendor/golang.org/x/text/unicode/bidi/tables10.0.0.go

@@ -1,6 +1,6 @@
 // Code generated by running "go generate" in golang.org/x/text. DO NOT EDIT.
 
-// +build go1.10
+// +build go1.10,!go1.13
 
 package bidi
 

vendor/golang.org/x/text/unicode/norm/composition.go

@@ -461,6 +461,10 @@ func (rb *reorderBuffer) combineHangul(s, i, k int) {
 // It should only be used to recompose a single segment, as it will not
 // handle alternations between Hangul and non-Hangul characters correctly.
 func (rb *reorderBuffer) compose() {
+	// Lazily load the map used by the combine func below, but do
+	// it outside of the loop.
+	recompMapOnce.Do(buildRecompMap)
+
 	// UAX #15, section X5 , including Corrigendum #5
 	// "In any character sequence beginning with starter S, a character C is
 	//  blocked from S if and only if there is some character B between S

vendor/golang.org/x/text/unicode/norm/forminfo.go

@@ -199,9 +199,14 @@ func buildRecompMap() {
 // Note that the recomposition map for NFC and NFKC are identical.
 
 // combine returns the combined rune or 0 if it doesn't exist.
+//
+// The caller is responsible for calling
+// recompMapOnce.Do(buildRecompMap) sometime before this is called.
 func combine(a, b rune) rune {
 	key := uint32(uint16(a))<<16 + uint32(uint16(b))
-	recompMapOnce.Do(buildRecompMap)
+	if recompMap == nil {
+		panic("caller error") // see func comment
+	}
 	return recompMap[key]
 }
 

vendor/golang.org/x/text/unicode/norm/iter.go

@@ -128,8 +128,9 @@ func (i *Iter) Next() []byte {
 func nextASCIIBytes(i *Iter) []byte {
 	p := i.p + 1
 	if p >= i.rb.nsrc {
+		p0 := i.p
 		i.setDone()
-		return i.rb.src.bytes[i.p:p]
+		return i.rb.src.bytes[p0:p]
 	}
 	if i.rb.src.bytes[p] < utf8.RuneSelf {
 		p0 := i.p

vendor/golang.org/x/text/unicode/norm/readwriter.go

@@ -60,8 +60,8 @@ func (w *normWriter) Close() error {
 }
 
 // Writer returns a new writer that implements Write(b)
-// by writing f(b) to w.  The returned writer may use an
-// an internal buffer to maintain state across Write calls.
+// by writing f(b) to w. The returned writer may use an
+// internal buffer to maintain state across Write calls.
 // Calling its Close method writes any buffered data to w.
 func (f Form) Writer(w io.Writer) io.WriteCloser {
 	wr := &normWriter{rb: reorderBuffer{}, w: w}

vendor/golang.org/x/text/unicode/norm/tables10.0.0.go

@@ -1,6 +1,6 @@
 // Code generated by running "go generate" in golang.org/x/text. DO NOT EDIT.
 
-// +build go1.10
+// +build go1.10,!go1.13
 
 package norm
 

vendor/golang.org/x/text/unicode/norm/transform.go

@@ -18,7 +18,6 @@ func (Form) Reset() {}
 // Users should either catch ErrShortDst and allow dst to grow or have dst be at
 // least of size MaxTransformChunkSize to be guaranteed of progress.
 func (f Form) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
-	n := 0
 	// Cap the maximum number of src bytes to check.
 	b := src
 	eof := atEOF
@@ -27,13 +26,14 @@ func (f Form) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error)
 		eof = false
 		b = b[:ns]
 	}
-	i, ok := formTable[f].quickSpan(inputBytes(b), n, len(b), eof)
-	n += copy(dst[n:], b[n:i])
+	i, ok := formTable[f].quickSpan(inputBytes(b), 0, len(b), eof)
+	n := copy(dst, b[:i])
 	if !ok {
 		nDst, nSrc, err = f.transform(dst[n:], src[n:], atEOF)
 		return nDst + n, nSrc + n, err
 	}
-	if n < len(src) && !atEOF {
+
+	if err == nil && n < len(src) && !atEOF {
 		err = transform.ErrShortSrc
 	}
 	return n, n, err
@@ -79,7 +79,7 @@ func (f Form) transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error)
 		nSrc += n
 		nDst += n
 		if ok {
-			if n < rb.nsrc && !atEOF {
+			if err == nil && n < rb.nsrc && !atEOF {
 				err = transform.ErrShortSrc
 			}
 			return nDst, nSrc, err