Consolidate dense inv methods to avoid overwriting (#20072)

Author: andreasnoack

base/linalg/dense.jl

@@ -583,6 +583,7 @@ sqrtm(a::Number) = (b = sqrt(complex(a)); imag(b) == 0 ? real(b) : b)
 sqrtm(a::Complex) = sqrt(a)
 
 function inv{T}(A::StridedMatrix{T})
+    checksquare(A)
     S = typeof((one(T)*zero(T) + one(T)*zero(T))/one(T))
     AA = convert(AbstractArray{S}, A)
     if istriu(AA)

base/linalg/generic.jl

@@ -693,8 +693,6 @@ trace(x::Number) = x
 
 #det(a::AbstractMatrix)
 
-inv(a::StridedMatrix) = throw(ArgumentError("argument must be a square matrix"))
-
 """
     inv(M)