What does this unknown source error mean?
===

I'm very new to Groovy. I'm solving a Fibonacci series with its properties. I have a groovy code like this : 


    a = new BigInteger[2][2]
    a[0][0] = 1
    a[0][1] = 1
    a[1][0] = 1
    a[1][1] = 0
    temp = new BigInteger[2][2]
    temp = a
    def testFun(def a,BigInteger n) {
    	if(n == 1)
    		return a
    	b = new BigInteger[2][2]
    	def sum = 0
    	for ( c = 0 ; c < 2 ; c++) {
    	            for ( d = 0 ; d < 2 ; d++ )
    	            {   
    	               for ( k = 0 ; k < 2 ; k++ )
    	               {
    	                  sum = sum + temp[c][k] * a[k][d];
    	               }
    	       b[c][d] = sum
                   sum = 0;
                }
             }
    	 	testFun(b,n-1)
    }
    c = new BigInteger[2][2]
    BigInteger n = 90
    if( n % 2 == 0 )
    { 	
    		c =  testFun(a,n.divide(2))
    		temp = c
    		c = testFun(c,2)
    }
    println c[0][1]

I'm getting answer like : 

    2880067194370816120

But when I change n value to say `5090` , I get a big error like this : 


	

    at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)
    	at fibb.testFun(fibb.groovy:24)
    	at fibb$testFun.callCurrent(Unknown Source)


What went wrong? Why I'm getting this error?
