Added custom error types

src/bpmlib/errors.go

@@ -0,0 +1,31 @@
+package bpmlib
+
+import (
+	"fmt"
+	"strings"
+)
+
+type PackageNotFoundErr struct {
+	packages []string
+}
+
+func (e PackageNotFoundErr) Error() string {
+	return "The following packages were not found in any repositories: " + strings.Join(e.packages, ", ")
+}
+
+type DependencyNotFoundErr struct {
+	dependencies []string
+}
+
+func (e DependencyNotFoundErr) Error() string {
+	return "The following dependencies were not found in any repositories: " + strings.Join(e.dependencies, ", ")
+}
+
+type PackageConflictErr struct {
+	pkg       string
+	conflicts []string
+}
+
+func (e PackageConflictErr) Error() string {
+	return fmt.Sprintf("Package (%s) is in conflict with the following packages: %s", e.pkg, strings.Join(e.conflicts, ", "))
+}